Dizziness
Dizziness is a term used to describe a range of feelings such as light-headedness, loss of bearing, or wooziness. It can feel like you’re drunk, sleepy, or like everything around you is spinning or unsteady (vertigo).
Dizziness is a common sensation that can be brought on by a wide range of causes. These causes are rarely life-threatening. Still, if you find yourself suddenly feeling dizzy often, you should see a doctor. Your dizziness may be caused by tachycardia [5] or arrhythmia [6] (irregular heartbeats). If tachycardia is the cause, you’ll typically experience it along with other symptoms, such as pain or discomfort in the chest and extremely fast heartbeats.
Fainting (Syncope)
Syncope [7] is the medical term for fainting or passing out. This temporary loss of consciousness is caused by a brief drop in the amount of blood supplied to the brain. Syncope is usually caused by a drop in heart rate or blood pressure, but it may also be caused by tachycardia.
The efficiency of blood supply to parts of the body may drop during tachycardia, even though the heart is pumping blood very fast. This can cause the amount of blood supplied to the brain to suddenly dip.
Many people experience irregular heartbeats associated with tachycardia just before an episode happens. Postural-Orthostatic Tachycardia Syndrome (POTS) [8] is caused by an accelerated heart rate that happens when a person stands after lying down or sitting for a while. It usually happens within 10 minutes of getting up and mostly affects women.